Low pressure both at the surface and the upper levels of the atmosphere passed through the region on the 12th. Showers and thunderstorms developed across the area. Despite relatively dry antecedent conditions, an unusually moist atmosphere combined with significant lift produce high rainfall rates sufficient for flash flooding across the Potomac Highlands. Rainfall amounts of over 3 inches in a several hour period were observed.

Event Narrative

Twin bridges near the intersection of North Mill Creek Road and South Mill Creek Road were closed due to running water.